What is a passive house?

Simply a passive house is passive in its use of heating and cooling.

Passive Homes Ltd are passive house builders and are experts in both new build and retrofitting to passive standards.

It requires no heating or cooling and fresh air is delivered to the house by means of a mechanical air ventilation system which recovers up to 95% of the heat of the expelled air.

The passive house therefore has no need for conventional heating systems such as oil, gas, or solid fuel heating.

The passive house is thermally efficient to the point that temperatures throughout the house are constant.

Heating is a combination of solar gain and use of heat from electrical and lighting appliances.

Human occupancy also contributes to the overall heating. A passive house is not different from traditional houses in appearance.

The house construction is based on standard building materials but which are used in a different manner to standard methodology.

When applied properly a passive home will result in excellent energy savings.

Passive precast construction will become the norm for large scale developments where standardised details and outcomes are required.

Insulation is very important in Passive homes. They use of most types of insulation is allowed as long as it meets U values.Rockwool insulation, spray insulation phenolic insulation are all allowed.

With passive homes the volumes of insulation are greater than traditional houses which has the added advantage of greater soundproofing to houses.

In particular passive wall thicknesses are thicker.


Passive windows have better U values Floor insulation is different and the way floor insulation is applied to concrete floors must meet specific design details.

Also the attic insulation is different.

The way attic insulation and crawlspace insulation is installed is different in that it must meet energy performance through eliminating thermal bridging.
Passive houses use solar gain and thermal mass to maximise heat gain.

Energy use by electrical goods and lighting are not included as they are outside of the design scope.

However is it noted that appliances are to be A rated and lighting to be energy efficient.

One of the unusual things about Passive housing is that it's measurable.

That means the energy efficiency is measurable.

Air tightness is tested to see the air tightness values.

Thermal imaging determines if the thermal envelope is broken

Finally the energy consumption can be measured over the long term to see the energy use.

Hot water use will be the same as a standard house but in most cases the use of renewable such as solar water heating are included in the design.

Passive houses maintain a steady comfort level throughout the house all year long.

Refits

The retrofitting of homes or extensions to a passive standard increases the level of comfort and decreases the energy levels.

The passive standard of construction and retrofitting insulation to the passive standards are essential to minimise energy losses and increase comfort.


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